Construction of concrete piles or the like



A. HOOD July 6, w43.

CONSTRUCTION OF CONCRETE PILES `OR THE LIKE Filed Oct. l, 1942 PatentedJuly 6, 1943` CONSTRUCTEON OF CONCRETE PILES OR THE LIKE Jandrew Hood,Carmarthenshire, Wales Application October 1, 1942, Serial No. 460,436

In Great Britain August 28, 1941 7 Claims. Y (Cl. 61-57) This inventionis for improvements in or relating to the construction of concrete pilesor the like by the method of driving a hollow piling tube fitted with aremovable closure member into the ground by percussion means andthereafter lling the tube with a fluid concrete mix and withdrawing thetube from the ground leaving the said closure member at the foot -of thenished pile. The invention is not concerned with screw-piles which aredriven into the ground,

after the manner of an auger, by the application of torsion to a hollowpiling tube tted with a fixed screwhead at its foot and left in situ asthe pile itself or as a part of a nished concrete pile.

According to the present invention there is provided a metal piling tubeclosed at the foot thereof with a removable closure member e. g aconventional shoe and having rigidly secured thereto, or formedintegrally therewith, evenly spaced inclined ribs running spirally roundthe -f outside of the tube, at least one rib extending alongsubstantially the whole length thereof. Where two ribs are provided itwill be appreciated that one may extend along substantially the wholelength of the tube whilst the other,

similarly inclined, extends only a short distance from the foot of thetube. The even spacing of the ribs round the tube prevents any lateralwandering of the piling tube whilst it is being driven into the ground.

Preferably the rib is formed by securing a channel section metal stripto the outer surface of the tube to leave a space between it and thetube through which fluid or air can pass.

It will be appreciated that the space between the channel section metalstrip and the outer surface of the tube may be used for the introductionof moisture to the foot of the tube while it is being driven through theground whenever a stratum of the earth is found to be unduly hard orotherwise dicult to penetrate. It will also be appreciated that the saidspace could, if desired, be used for passing a grouting mixture ofcement grout (if desired also containing sand) down to the lowermostedge of the tube while it is being driven into or withdrawn from theground to eiiect cementation of any particular Astratum of the ground e.g. a porous sandy or gravel stratum When in use, the tube is freelypositioned in a collar secured to the base of a piling frame whichcollar is formed with a groove, shaped to engage with the rib, on thetube to ensure rotation of the tube during its axial movement.

The invention also includes within its scope the construction ofconcrete piles, utilising a tube constructed as above described.

The present invention provides great improvements in relation toconcrete piles as the spiral rib projections running around the pileshaft greatly enhance the frictional Value of the pile and consequentlyits `load-bearing capacity by developing the maximum frictional valueeven in the weakest of ground strata. In fact the pile of the presentinvention is a Combination of the shaft and screw piles and possessesall the advantages of both but with none of their disadvantages. Thenormal desired diameter of the pile is denitely maintained throughoutits whole length whilst the ribs act as load-bearing agents and aord aconsiderable increase over the normal diameter of the pile. 'f

The invention can'be put into effect in a very simple manner by means ofa simple and inexpensive modication of any standard pile-drivingequipment, for instance, the spiral ribs can be afxed t0 a standardpile-driving tube whilst at the same time the conventional piling framecan be used with a very slight modification.

and also to the reduction of suction forces Where hollow ribs are used.

The length of the piling tube can be adjusted to suit the circumstancesand the piling frame can, by the adoption of standard lengths of pilingtube, be standardised to a conveniently manageable height as, forexample, 35 to 40 feet.

The following is a description of one embodiment of the inventionillustrating the construction of the tube and its method of use in theformation of a concrete pile described with reference to theaccompanying drawing in which:

Figure 1 is a side elevation of a piling tube,

Figure 2 shows the piling tube arranged in relation to a piling frame,

Figure 3 shows a View of the concrete pile of the invention in positionin the ground,

Figure 4 is a cross section of Figure 1 along the line A-A,

Figure 5 is an enlarged detailed View of the lower part of the tubeshown in Figure 1 and Figure 6 is a cross section of the concrete pileon the line B-B of Figure 3.

The tube a, which may be of any convenient diameter depending upon thediameter of the concrete pile which it is desired to form, is a hollowcylindrical member provided at its foot with the ordinary customarycircular metal shoe b which is provided with a projection lc which ntswithin the lowermost end of the tube with the ange P abutting the end ofthe tube as best seen in Figure 5. Fixed rigidly to the external surfaceof the tube are two metal rib projections c, d, one of which (c) extendsfor the full length of the tube in the form of a slow spiral and theother of which (d) extends up for a short distance from the bottom ofthe tube and is inclined to the axis of the tube at the same angle asthe .full-length rib. The short rib is arranged so as to bediametrically opposite the long rib so that during the movement of thetube into the ground, the lateral thrust caused by the long rib is, atthe foot, prevented from causing a lateral wandering of the piling tube.

The bottom ends of both ribs are cut at an angle so as to form a cuttingedge in order that as the tube is driven into the ground two spiralgrooves will be cut in the surrounding ground.

The two ribs are formed by bending a piece of bridge rail into thedesired form and securing it to the outer surface of the tube by weldingalong both its flanges over the whole length thereof; the short rib isof course similarly formed; it will of course be understood, however,that the ribs may be formed in any other convenient manner.

The tube and rib may be in one length L or may be in any desired numberof lengths S, Si (so as to permit of convenience in handling theseparate lengths) the various lengths being secured together preferablyby means of screwed joints.

The rib is preferably of such a pitch as to have :one revolution in alength of tube which is from twenty to twenty-five times its diameter.

The top end of the tube is provided with the conventional driving headand helmet m.

In use, the tube is clamped in an ordinary loose collar r which travelsdown with the tube and is secured to the leaders of a piling frame withthe shoe b penetrating the ground in the selected pile position. At ornear to the ground surface the tube is clamped by a heavy guide collare, secured to the base of the piling frame and formed with an internalgroove arranged to engage the rib so as to ensure that the tube rotates,as it is driven into the ground, in such a manner as to cut cleangrooves through the ground. The guide collar may be provided with strongsprings suitably disposed to take up variations in the drive.

When the shoe has been placed on the ground in a selected position andthe tube has been lowered on to it and the guide collar e has beenclamped around the tube a, then the tube can be driven into the groundby means of any conventional hammer indicated generally by H. It will beunderstood that owing to the loose fit between the tube a and the shoeb, the shoe does not itself necessarily revolve and will remain in thebottom of the hole and at the foot of the pile when the tube iswithdrawn.

When the tube has been driven a sufficient distance into the gro-und theoperation of forming the concrete piie may then commence.

A liquid concrete mixture is poured into the middle of the tube a so asto fill up the space within and the tube is then withdrawn by theconventional method of reversing the action of the driving hammer H soas to drive the tube in an upward direction, or alternatively the tubemay be pulled out of the ground; the tube is still in position in theguide-collar and will consequently rotate as it is withdrawn therebypreserving the shape of the grooves in the ground. It will of course beappreciated that where a reinforced pile is required, a steel cagereinforcement f is introduced into the tube preferably so as to rest onthe upper surface of the shoe.

It will be understood that as the tube is extracted from the ground theuid concrete mixture within the tube will completely ll the hole,including the groove or grooves formed by the ribs, and consequently thenished concrete pile will be in the form of a concrete core with twospiral ribs, g formed around it along the whole of its length; thesespiral ribs have an important effect in providing additional frictionalcontact with the surrounding ground so as more readily to prevent anymovement of the pile by increasing the effective diameter of the pilefrom Di to D2 as seen in Figure 6 thereby increasing its loadbearingcapacity.

It will be appreciated that certain modificatiens may be made to theprocedure described above, for instance instead of the tube beingprogressively withdrawn from the ground it may be gradually withdrawnwith an up and down movement which has the effect of tamping theconcrete so as to form a closer and more compact pile or it may bevibrated mechanically during its withdrawal to increase the density ofthe concrete.

It will be appreciated that although the foregoing description has madereference only to a single rib extending along the whole length of thetube, any desired number of ribs c, may be arranged evenly spaced aroundthe periphery of the tube in which case the short length of tube couldbe dispensed with.

What I claim is:

l. A piling tube adapted to be closed at the foot thereof with aremovable closure member and driven into the ground by percussion meansfor the formation of an in situ concrete pile comprising a metal pilingtube provided with a number of evenly spaced inclined ribs running roundthe outside of the tube, at least one of said ribs extending alongsubstantially the whole length thereof and being hollow and adapted topermit the passage of liquid to the foot of said tube.

2. A piling tube adapted to be closed at the foot thereof with aremovable closure member and driven into the ground by percussion meansfor the formation of an in situ concrete pile comprising a metal pilingtube provided with two diametrically opposite inclined ribs runninground the outside of the tube, at least one of said ribs extending alongsubstantially the whole length thereof and being hollow and adapted topermit the passage of liquid to the foot of said tube.

3. A piling tube adapted to be closed at the foot thereof with aremovable closure member and driven into the ground by percussion meansfor the formation of an in situ concrete pile comprising a metal pilingtube provided with a number of evenly spaced inclined hollow ribsrunning round the outside of the tube, at least one of said ribsextending along substantially the whole length thereof.

4. A piling tube adapted to be closed at the foot thereof with aremovable closure member and driven into the ground by percussion meansfor the formation of an in situ concrete pile comprising a metal pilingtube provided with two diametrically opposite inclined hollow ribsrunning ber of evenly spaced inclined hollow ribs formed ofchannel-section metal strip secured to the outside of the tube andrunning round the outside of the tube, at least one of said ribsextending along substantially the whole length thereof.

6. A piling tube adapted to be closed at the foot thereof with a removalclosure member and4 driven into the ground by percussion means for theformation of an in situ concrete pile comprising a metal piling tubeprovided with two diametrically opposite inclined hollowribs formed ofchannel-section metal strip secured to the outside of the tube andrunning round the outside of the tube, at least one of said ribsextending along substantially the whole length thereof.

7. A piling tube adapted to be closed at the foot thereof with aremovable closure member and driven into the ground by percussion meansfor the formation of an in situ concrete pile comprising a metal pilingtube provided with a number of evenly spacedinclined ribs'running roundthe outside of the tube, at least one of said ribs being hollow andextending along substantially the Whole length thereof said ribs beinginclined at an angle of from l in 20 to 1 in 25.

ANDREW HOOD.

